This Is the Number One Cause of Foodborne Illness Outbreaks. Here's How to Stay Safe

More than 100,000 people were sickened by food-related illness outbreaks between 2009 and 2015, according to a new analysis by the U.S. Centers for Disease Control and Prevention (CDC). And the food that made more people sick than any other? Chicken. It was confirmed as the cause of more than 3,000 (about 12%) of those cases.

Pork and seeded vegetables came in second and third for number of illnesses caused, both with more than 2,500 cases or about 10% each. Fish and dairy caused more individual outbreaks than any other food groups, according to the analysis, but those outbreaks were smaller and sickened fewer total people.

The report’s findings may not be surprising for anyone who’s ever taken a cooking class or cut into their chicken dinner to make sure it’s cooked all the way. Just last week, a court case made headlines after a healthy and fit mother of two died after eating uncooked chicken at a hotel in Greece. (A coroner said the woman likely contracted E. coli from the raw poultry.)

But the CDC says that its deep data dive, published in the agency’s Morbidity and Mortality Weekly Report, is important for the food-safety industry: Only a small percentage of the 9.4 million foodborne illnesses reported each year are associated with recognized outbreaks, the CDC said in its report—but studying those outbreaks can still provide valuable insight into how to keep consumers out of harm's way.

Between 2009 and 2015, according to the report, 5,760 outbreaks were reported to the CDC. (An outbreak is defined as anytime two or more cases of a similar illness result from the ingestion of a common food.) Those outbreaks resulted in 100,939 illnesses, 5,699 hospitalizations, and 145 deaths, and they occurred in all 50 states as well as Washington D.C. and Puerto Rico.

About half of those outbreaks were traced back to a single virus, bacterium, or other type of toxin. Norovirus, which can be transmitted when infected people handle and contaminate a food supply, was the leading cause—which highlights the need for food-safety improvements “targeting worker health and hygiene in food service settings,” the CDC’s report states. Specifically, it says, rules that keep sick workers away from food, prohibit bare-hand contact with ready-to-eat food, and ensure appropriate hand washing need to be better enforced.

Salmonella—a bacteria that’s commonly found in raw chicken, eggs, red meat, and contaminated produce—was the second most common cause of outbreaks. Together, outbreaks caused by Listeria, Salmonella, and E. coli were responsible for 82% of all hospitalizations and 82% of deaths.

The report also sheds some light onto where these outbreaks begin. Of the outbreaks that reported a single location of food preparation, 61% cited restaurants as their starting point. Catering and banquet facilities were cited in 14% of those outbreaks, and private homes in 12%. Institutions (such as schools) were responsible for a smaller number of outbreaks but sickened more people per outbreak than any other source.

Foodborne illness outbreaks have been reported voluntarily by state and local health departments since the 1960s, but 2009 was the first year the CDC launched a web-based reporting platform. The report mentioned a few specific outbreaks that occurred during its study period, including ones linked to pine nuts, cucumbers, eggs, cantaloupes, caramel apples, and, yes, chicken.

The CDC’s report concludes that, despite recent advances in food safety in the United States, “foodborne disease outbreak remains a serious public health problem.” It also notes an important caveat: Because the agency only looked at illnesses that affected two or more people, it’s unclear how much of a role these specific food sources and outbreak locations play in individual illness that aren’tassociated with outbreaks. (In other words, foodborne illnesses can be caused by many different foods in many different settings—not just uncooked chicken at restaurants.)

Byron Chaves-Elizondo, PhD, assistant professor and food safety extension specialist at the University of Nebraska-Lincoln, says it's important to put the CDC's findings in perspective. (He was not involved in the new report.) Yes, he says, the percentage of illnesses in this report attributed to chicken is significant—"but so is the burden attributed to fish, dairy, or produce, for example, so we can't get carried away by the numbers," he adds.

Plus, he points out, many of the outbreaks included in the study were not able to be traced to a specific food. "That is concerning, and public health authorities continue to make great strides to reduce that gap," he says.

The fact that most illnesses in the report were linked to restaurants also isn't surprising, says Chaves-Elizondo, since they serve so many more people than private residences. "We often don't have 100 people at home, and if we do, we typically cater the food from a restaurant," he says. But home cooks "should not get too comfortable," he adds, since contamination can and does occur in all types of kitchens.

How to stay safe when cooking at home

Two ways to protect yourself from foodborne illnesses are to always cook poultry and ground beef thoroughly, the CDC advises, and to refrigerate leftovers promptly after eating. (Cooking poultry to 145 degrees and red meat to 160 degrees will kill most foodborne pathogens.) "Using a food thermometer is the best way to know the internal temperature of the product reached the safety value," says Chaves-Elizondo. "Pink/not pink or chewy/not chewy don’t really cut it."

It’s also smart to avoid recipes that call for raw eggs (including mayonnaise, salad dressings, ice creams, and cake frostings), and if you marinate raw meat or poultry, do so in the fridge—and don't use leftover juices to baste the finished product. "Definitely do not assume that meat marination is an effective antimicrobial intervention," says Chaves-Elizondo.

Watch out for cross-contamination, too—another common way that pathogens can be transmitted. For starters, don't wash raw chicken before cooking it: "The droplets and aerosols can actually spread Salmonella and Campylobacter& to clean surfaces, and they can establish a niche in your sink if you don’t sanitize it often and properly," says Chaves-Elizondo. "Rather, remove any unwanted tissue with shears, discard in the trash, and cook your poultry thoroughly."

If you're worried about the juices that chicken is often packaged in, sanitize the package before opening it and drain it carefully to avoid splashes, says Chaves-Elizondo. Those juices could in fact harbor Salmonella if the chicken itself is infected, he says, "but chances are actually very slim."

Finally, keep uncooked meats and poultry separate from everything else in your kitchen, use separate cutting boards when preparing them, and make sure to wash your hands—and all surfaces and utensils involved—with soap and water after you handle them.